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Topic Review (Newest First)

05-25-2013 10:14 PM

big gear head

I've never been able to read a pattern with that blue stuff. I can't say for sure.

05-25-2013 09:32 PM

S10xGN

BGH,

I was bad! I went out and finished torquing the ring gear bolts and setting the backlash (all with my left arm). Using my homemade yellow "paste" I changed pinion shims from 0.027" to 0.038" to 0.050" and could not discern any change in pattern, at all. After wiping it all down, sticking in a single 0.020" shim, setting b/l at 0.008", and using some Prussian blue compound, this is what I'm now looking at. By then, my arm was getting sore so I quit. The coast side is fairly pronounced, but the drive side doesn't show as well. What's the verdict?

Russ

05-23-2013 12:30 PM

big gear head

I'm sure that there is a tool for that, but I don't have one. If I can turn it by hand then it's loose. Most of the time they don't turn when I torque the lug nuts.

Good luck with the shoulder. I just took the ice pack off of mine.

05-23-2013 11:46 AM

S10xGN

OK, looks like I'm gonna be out of commission for a few months. If I can find this thread when I get back to it I'll update it, otherwise I'll start over...

BGH, what do you use to check the breakway at the axle? Is there some kind of adapter to go from the lug studs to a torque wrench?

Russ

05-20-2013 07:40 PM

S10xGN

Quote:

Originally Posted by big gear head

Are you using a axle shaft in both sides when you are checking this? If you don't have a shaft in the side with the split gear and clutch hub then the break away torque is going to be much less because these two parts must have a shaft to lock them together.

Ya know? I did not! I just had the pinion-side axle in a vise and nothing in the clutch side. I guess when it slips like this, it throws off the alignment between the side gear and clutch hub... Thinking back, it was pretty tight when I had both axles in it and was (trying to) turn the assembly using the tires as handles. But I'm pretty weak in the arms right now so thought it may have been me. Got an appt. with the shoulder doc Wed to at least get a diagnosis. I did find a diagram of the factory tool with dimensions, so may make one to try out.

Russ

05-20-2013 11:48 AM

big gear head

Are you using a axle shaft in both sides when you are checking this? If you don't have a shaft in the side with the split gear and clutch hub then the break away torque is going to be much less because these two parts must have a shaft to lock them together.

05-19-2013 09:25 PM

S10xGN

Quote:

Originally Posted by big gear head

I'm having memory problems with the thrust washer. I can't remember how it fits. I can relate to the shoulder problem. I'm having shoulder and elbow problems. One in one arm and one in the other.

I got wondering about it and did some measuring. Here it is drawn in orange. The clutch pack, even with no shims, is tall enough that the washer doesn't feel any load. With normal shimming, it should be around .060" loose. Theoretically, until the clutches go away...

I got this e-mail from QP tonight:

Quote:

Russ-
The new aggressive units come with 250 ft/lbs of breakaway on the clutches and the new smooth units come with around 150-175 ft/lbs of breakaway on the clutches. We test it by putting a splined section into each side of the unit and torqing one side until it slips.

Looks like I'm still ways off on how to do this. After watching Tom's vids, I can see what would happen if a unit is overshimmed. I have no idea how QP is getting their units to 250# without overshimming them. Guess I should have just bought another NASCAR locker off E-Bay and not had to go through all this...

Russ

05-19-2013 08:58 PM

big gear head

I'm having memory problems with the thrust washer. I can't remember how it fits. I can relate to the shoulder problem. I'm having shoulder and elbow problems. One in one arm and one in the other.

05-19-2013 07:59 PM

S10xGN

OK, round #3 with this thing...

Removed the springs and assembled the unit with a single 0.020" shim. Burnished the clutches 20 turns in each direction by setting a wheel/tire on the floor, sticking an axle in the hub, placing the diff on the axle, sticking the other axle in the diff, then another wheel/tire on that axle, then round and round she goes! This was easy with little resistance. Added another 0.020" shim and it would not budge. Removed that shim and added an 0.013" shim (where I was originally). This was about like the resistance in the Tom's vid with the exception of one tight spot for about 30° of rotation. After making 20 rounds in each direction, things got no better, so I assembled the diff with 0.033" shims and the tight spot. When I was seating the ring gear, it seemed to want to "break away" and rotate around 45 ft-lbs again. My shoulder quit before I did, so it's waiting on a "mood adjustment" to torque the ring gear bolts and reassemble it. Is this as good as it'll get?

One thing I did ponder on, the thrust washer just "floats" until the clutch pack wears enough for the clearance to disappear, correct?

Watch these. This is how I've done it for about 30 years. You have to set the Ford Trac Lock a little more loose than the Eaton Posi, but it works the same. Leave the springs out until you have the shims right and then put the springs in.

05-18-2013 10:54 AM

S10xGN

Quote:

Originally Posted by big gear head

The springs are all the same. Some people leave 2 springs out if they want it to be a little softer for street use. I don't know of any manual. I shim the clutches in the 9 inch a little looser than I do in a Eaton Posi. If you shim them tight in the 9 inch they will pop and make a lot of noise.

I don't mind the noises, more concerned with breakage. Will this be potential problem if it's tight enough to make noise?

Quote:

Originally Posted by big gear head

I don't set the clutches like that. I put a shim in and assemble the differential without the springs, then stick it on an axle stub in a vice and turn it. If the resistance is too high I use a thinner shim. If it isn't enough then I use a thicker shim. When the resistance is where I want it then I put the springs in and call it good enough. You can't assemble one of these as tight as you do a Eaton Posi. If you get it too tight then it will pop and growl when turning a corner.

Are you measuring or going by feel? I'm not understanding how it wouldn't slip with the springs not there...

Quote:

Originally Posted by big gear head

If that's an accurate pattern then it looks great. That's almost complete tooth contact. I don't think I have ever seen one with that much contact area before. May just be the grease that you used.

The clutches should be tight enough that you can torque the ring gear bolts and not ever feel anything slip. I've had to take these apart and remove shims because they locked up too much.

I found some "recipes" for the compound that I'll try later, I've got to give my shoulder some rest. I don't want this diff loose enough to smoke the clutches. Is there a more "scientific" way of measuring? Perhaps somehow measure the gap between the spring plate and the case without the springs, then adjust it with shims until there's a given clearance for them? Say the spring plate (spring free height) is 0.200", could you then shim it until the plate's compressed height is (maybe) 0.050"? Would that leave enough room for heat expansion without bottoming the springs?

Thanks again!

Russ

Oh, and my breakaway reading is prolly a bit higher than 45# as I was pulling from one of the ring gear bolts and not the center of the axle which would give more mechanical advantage...

05-17-2013 10:58 PM

big gear head

You can get the gear marking compound at many GM dealers. It's hard to use a press and get the gear on straight. You have a pretty good way of doing it. I don't know why your clutches are not holding. The springs should be enough to keep you from being able to turn it. I don't set the shims the way you are doing it.

05-17-2013 09:49 PM

S10xGN

Quote:

Originally Posted by big gear head

If that's an accurate pattern then it looks great. That's almost complete tooth contact. I don't think I have ever seen one with that much contact area before. May just be the grease that you used.

The clutches should be tight enough that you can torque the ring gear bolts and not ever feel anything slip. I've had to take these apart and remove shims because they locked up too much.

I thought I'd read somewhere that 45# breakaway was the factory setting. So you think I should add more shims?

What's a good trick for installing the ring gear on the case? I've had zero luck with my press (it always wants to go on crooked). I've been using 3 old Buick head studs with spacers to pull it on far enough to get the bolts started, but my shoulder really doesn't like all that pulling. You think Advance or Autozone would have the pattern compound?

Russ

05-17-2013 08:36 PM

big gear head

If that's an accurate pattern then it looks great. That's almost complete tooth contact. I don't think I have ever seen one with that much contact area before. May just be the grease that you used.

The clutches should be tight enough that you can torque the ring gear bolts and not ever feel anything slip. I've had to take these apart and remove shims because they locked up too much.

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